Ultra short-throw projectors are great for rooms where space is at a premium, as they create a huge image without needing to be miles away from your projection surface. The Optoma EH320UST can create a 2m diagonal image from just 45cm away, making it one of the shortest throw distances we've come across.

The maximum throw distance is 59cm, at which point the projector produces a huge 2.54m image. No matter the size, images look super sharp thanks to the 0.65in DLP chip's 1,920x1,080 Full HD resolution. The 4,000 lumen lamp helps to produce an incredibly bright image that easily overcomes strong overhead lighting.

Actual colour vibrancy isn't particularly great, however. Because the projector prioritises brightness and contrast for easy viewing in even the most difficult environments, bright colours appear a little washed out. By default, the "BrilliantColor" setting is switched on, and you'll definitely want to keep it at the maximum level to get the most eye-catching colours. We found the "Bright" colour preset offered the best overall image quality, although "Presentation" mode was a little less harsh on the eyes so is probably a better bet for longer stints.

Text on presentations is easy to read, though, and the claimed 20,000:1 contrast ratio means even darker images are pretty well served, too.

The projector lens is mounted near the rear of the unit, meaning all the connectors are right at the front, which results in minimum cable mess as you can easily route cables away from the projector without obscuring the lens. The projector can be wall or ceiling mounted, or placed on a table, although considering its large size and 5kg weight, mounting will be preferable.

The EH320UST is extremely versatile when it comes to connectivity. There are two HDMI ports, two VGA ports, a composite connector, two 3.5mm audio jacks, a network cable for monitoring and a USB port. The USB port is only for connecting to computers for control purposes; it can't be used play media or open files natively, although this is hardly an issue for an office projector.

While 16W may sound like a lot, in our testing we were very disappointed with the EH320UST's sound quality. It was able to reach some high volumes, but there was almost no bass presence and high frequency sounds such as speech actually caused some distortion and rattled the projector's plastic housing. If you're in a larger room and want to fill it with sound, you'll need to invest in separate speakers. At least fan noise is reasonably quiet - 28dB is definitely audible but it's reasonably well muffled by the chassis and isn't a distraction.

The EH320UST is available with an optional interactive TouchBeam module, which can be mounted to any projection surface to turn it into an interactive touchscreen. The TouchBeam module is powered by the projector, and connects to your PC or laptop over USB. It effectively acts as a separate input device and has multiple touch points, meaning you can use your fingers (or the supplied pens) to perform multi touch gestures or have multiple contributors drawing on the screen at once. Setup is a little complicated and requires some fiddly manual adjustment to get everything working correctly, but after the initial setup the only time you'll need to mess with calibration options is if the projector or board gets a knock and is moved slightly.

The touch module produces an infra-red curtain of light, which is seen by a sensor on the projector. A touch is registered wherever the beam is broken, meaning any completely flat surface is suitable. Touch inputs are extremely accurate, even when multiple people were drawing at once. We did sometimes run into issues when two users got too close to one another, with the sensor getting slightly confused as to which touch point belonged to which person. The addition of touch is pretty expensive, but for a projector setup where presentations can turn into ideas meetings, it could be very useful. Optoma doesn't supply or recommend any specialised whiteboard software, although we found the ability to draw on documents in Microsoft Office 2013 and MS Paint perfectly usable.

Overall, the Optoma EH320UST is a versatile projector that can fit into even the tightest spaces. With plenty of inputs and a bright 4,000 lumen lamp, it's usable in any challenging office environment, although you do pay for this with a slight lack of colour vibrancy. The optional interactivity features are accurate and fun to use, and our only real reservation about the whole product are its disappointing speakers, which will result in extra money being spent on an external set when you maybe hadn't planned on doing so.

If you're looking for a short-throw projector for the living room, the Optoma GT1080 is a much better option, with vibrant colours and optional 3D making it perfect for movies and games.